1. Field of the Invention
This invention relates to polyurethane products, naturally free of polymerization catalyst residues. Particularly the invention relates to a process for producing polyurethanes without the use of polymerization catalyst at initial processing temperature in the ambient room temperature range.
2. Description of the Prior Art
Conventionally the reaction of organic "di or poly" isocyanates with organic "di or poly" hydric alcohols to produce polyurethane product is carried out with the help (in the presence of) a polymerization catalyst, or at an elevated, superatmospheric, temperature to initiate the polymerization reaction which then carries on aided by the exothermic heating. Both reaction aids may be used in some cases. Organic catalyst tends to take part in the reaction affecting the polymer product properties; or decomposes to introduce, frequently, color problems into the polymer product. Metal catalyst, especially the tin catalysts, affect the polymer product quality; tin residues make the product humidity sensitive, as well as adversely affecting other properties. In long term usage, such as in furniture usage, catalyst residues may cause degradation particularly in color changes, and decreasing the toughness of the product. Reaction at higher elevated temperatures tends to impair properties of the polyurethance product by causing adverse secondary reactions.